Underestimation of carotid stenosis in bradycardia.

Bradycardia may lead to an underestimation of carotid stenosis by duplex ultrasonography. An 83-year-old man with asymptomatic bradycardia was referred to our institution after magnetic resonance angiography revealed greater than 90% stenosis of the proximal left internal carotid artery (ICA). Two separate carotid duplex examinations were subsequently performed at different vascular laboratories within our institution. Both studies showed elevated (but borderline for the highest category of stenosis) peak systolic velocities with relatively low end-diastolic velocities (EDVs). Angiography demonstrated more than 90% stenosis of the left ICA. Carotid endarterectomy was then performed. In conclusion, interpreting physicians and vascular ultrasound technologists should be aware of the spurious decrease in EDV that accompanies bradycardia. Further imaging may be warranted when revascularization is a consideration for bradycardic patients with borderline results on carotid duplex ultrasonography.